For medical applications it is advantageous to determine the magnetic resonance (MR) spectrum of a particular area or volume of a patient's body, i.e. to measure localized magnetic resonance spectra in vivo. This information is used e.g. to investigate metabolic processes and to diagnose pathologies (e.g. tumors). However, production of such in vivo spectroscopic information presently requires a comparatively large quantity of data.
For example, let it be assumed that a particular square image of a patient's body contains both muscle and tumor. If the maximum dimension of the tumor is only one-eighth as large as the length of each side of the square, at least 64 (8.sup.2) phase-encoded spectroscopic signals are required by the Fourier transform spectroscopic imaging method. This is because 8 phase-encoding steps along each of the two directions are required to obtain a resolution which is fine enough to localize the tumor.
This problem becomes even more acute where a user requires a localized MR spectrum in a three-dimensional volume of interest rather than in a two-dimensional area of interest. For example, let it be assumed that a three dimensional cubic volume contains both muscle and tumor and that the dimensions of the tumor are approximately one-tenth the length of each side of the cube. In order to perform transform spectroscopic imaging, it would then be necessary to acquire data from at least 1000 (=10.sup.3) phase-encoded signals. This would be time consuming and would reduce patient throughput through the MR unit.
It would be advantageous to reduce the quantity of data required to derive an MR spectrum for a particular area or volume of interest.